Flat-panel detector



FIG. 1 is a top and left side perspective view of a flat-panel detector showing our new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a left side elevation view thereof;

FIG. 4 is a right side elevation view thereof;

FIG. 5 is a front elevation view thereof; and,

FIG. 6 is a rear elevation view thereof.

The broken lines in the drawings illustrate portions of the flat-panel detector that form no part of the claimed design. 

CLAIM The ornamental design for a flat-panel detector, as shown and described. 